mid49

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mid49

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#f8f9fa;text-align:center;font-size:1.1em;">MID49</th></tr>
<tr><th>Symbol</th><td>MID49 (MIEF2, SMCR7L)</td></tr>
<tr><th>Full Name</th><td>Mitochondrial Dynamics Protein Mid49</td></tr>
<tr><th>Chromosome</th><td>5q31.2</td></tr>
<tr><th>NCBI Gene ID</th><td>[84752](https://www.ncbi.nlm.nih.gov/gene/84752)</td></tr>
<tr><th>OMIM</th><td>[616121](https://www.omim.org/entry/616121)</td></tr>
<tr><th>Ensembl</th><td>[ENSG00000156535](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000156535)</td></tr>
<tr><th>UniProt</th><td>[Q9H0W4](https://www.uniprot.org/uniprot/Q9H0W4)</td></tr>
<tr><th>Associated Diseases</th><td>[Alzheimer's disease](/diseases/alzheimers-disease), [Parkinson's disease](/diseases/parkinsons-disease), ALS, Huntington's disease</td></tr>
</table>
</div>

Overview

MID49 (also known as MIEF2 - Mitochondrial Elongation Factor 2, or SMCR7L - Smith-Magenis Syndrome Chromosome Region, candidate 7-like) is a mitochondrial outer membrane protein that plays a critical role in regulating mitochondrial dynamics. As a member of the MiD49/51 family of mitochondrial division proteins, MID49 acts as an adaptor for the recruitment of the large GTPase [DRP1](/proteins/drp1-protein) (DNM1L) to mitochondria, thereby controlling the balance between mitochondrial fission and fusion [gomes2011](https://pubmed.ncbi.nlm.nih.gov/21619488/).

...

mid49

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#f8f9fa;text-align:center;font-size:1.1em;">MID49</th></tr>
<tr><th>Symbol</th><td>MID49 (MIEF2, SMCR7L)</td></tr>
<tr><th>Full Name</th><td>Mitochondrial Dynamics Protein Mid49</td></tr>
<tr><th>Chromosome</th><td>5q31.2</td></tr>
<tr><th>NCBI Gene ID</th><td>[84752](https://www.ncbi.nlm.nih.gov/gene/84752)</td></tr>
<tr><th>OMIM</th><td>[616121](https://www.omim.org/entry/616121)</td></tr>
<tr><th>Ensembl</th><td>[ENSG00000156535](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000156535)</td></tr>
<tr><th>UniProt</th><td>[Q9H0W4](https://www.uniprot.org/uniprot/Q9H0W4)</td></tr>
<tr><th>Associated Diseases</th><td>[Alzheimer's disease](/diseases/alzheimers-disease), [Parkinson's disease](/diseases/parkinsons-disease), ALS, Huntington's disease</td></tr>
</table>
</div>

Overview

MID49 (also known as MIEF2 - Mitochondrial Elongation Factor 2, or SMCR7L - Smith-Magenis Syndrome Chromosome Region, candidate 7-like) is a mitochondrial outer membrane protein that plays a critical role in regulating mitochondrial dynamics. As a member of the MiD49/51 family of mitochondrial division proteins, MID49 acts as an adaptor for the recruitment of the large GTPase [DRP1](/proteins/drp1-protein) (DNM1L) to mitochondria, thereby controlling the balance between mitochondrial fission and fusion [gomes2011](https://pubmed.ncbi.nlm.nih.gov/21619488/).

The proper regulation of mitochondrial dynamics is essential for neuronal health, and dysfunction in MID49-mediated mitochondrial quality control mechanisms is strongly implicated in the pathogenesis of neurodegenerative diseases including [Alzheimer's disease](/diseases/alzheimers-disease) (AD), [Parkinson's disease](/diseases/parkinsons-disease) (PD), amyotrophic lateral sclerosis (ALS), and [Huntington's disease](/diseases/huntingtons-disease) [wang2017](https://pubmed.ncbi.nlm.nih.gov/29193486/).

This comprehensive page covers MID49's molecular functions, its critical role in neuronal biology, disease associations, signaling pathways, therapeutic implications, and key research findings relevant to neurodegeneration.

Gene and Protein Structure

Gene Organization

The MID49 gene is located on chromosome 5q31.2 and encodes a protein of 452 amino acids with a molecular weight of approximately 49 kDa, hence its name "Mid49" [gomes2011](https://pubmed.ncbi.nlm.nih.gov/21619488/). The gene is evolutionarily conserved, with orthologs present in yeast (Mdm34) and other eukaryotes.

Protein Architecture

MID49 possesses several key structural features:

N-terminal cytosolic domain: Contains a proline-rich region that may serve as a binding platform for SH3 domain-containing proteins

Transmembrane anchor: A single-pass transmembrane domain anchors the protein to the mitochondrial outer membrane

C-terminal cytosolic domain: Interacts with DRP1 and regulates its GTPase activity

MIEF domain: The MiD family-specific domain involved in oligomerization and DRP1 recruitment

The protein functions as a dynamic regulator, capable of both promoting and inhibiting mitochondrial fission depending on cellular context and phosphorylation state.

Relationship to MID51

MID49 shares significant homology with its paralog [MID51](/genes/mief1) (MIEF1), and these proteins have both overlapping and distinct functions:

| Feature | MID49 | MID51 |
|---------|-------|-------|
| Length | 452 aa | 463 aa |
| Tissue expression | Broad | Broad |
| DRP1 recruitment | Inducible | Constitutive |
| Fission vs fusion bias | Context-dependent | Fusion-promoting |

Role in Mitochondrial Dynamics

Mitochondrial Fusion and Fission

Mitochondria are highly dynamic organelles that constantly undergo fusion and fission, a process essential for:

Mitochondrial quality control: Removing damaged mitochondria through mitophagy
Energy distribution: Ensuring equitable distribution of mitochondria throughout neurons
DNA maintenance: Facilitating mitochondrial DNA (mtDNA) mixing and repair
Apoptosis regulation: Controlling cytochrome c release

Mermaid diagram (expand to render)

DRP1 Regulation

[DRP1](/proteins/drp1-protein) (Dynamin-related protein 1) is the principal mediator of mitochondrial fission. MID49 regulates DRP1 through several mechanisms:

Adaptor function: MID49 recruits DRP1 to the mitochondrial surface

GTPase regulation: MID49 modulates DRP1's GTPase activity

Oligomer formation: MID49 can form oligomers that serve as docking sites for DRP1

Phosphorylation sensitivity: MID49's interaction with DRP1 is regulated by phosphorylation

The balance between fusion and fission is critical for neuronal survival. Excessive fission leads to mitochondrial fragmentation and apoptosis, while excessive fusion can result in elongated, dysfunctional mitochondria [head2014](https://pubmed.ncbi.nlm.nih.gov/24732029/).

Mitochondrial Quality Control

MID49 plays a central role in mitochondrial quality control through:

Fission-dependent mitophagy: Segregation of damaged mitochondrial segments for degradation

Mitochondrial-derived vesicles (MDVs): Formation of vesicles for selective mitochondrial turnover

Apoptosis regulation: Control of cytochrome c release through fission regulation

Metabolic adaptation: Adjusting mitochondrial network morphology to cellular energy demands

Role in Neurodegenerative Diseases

Alzheimer's Disease

In [Alzheimer's disease](/diseases/alzheimers-disease), MID49 function is compromised through multiple mechanisms:

Expression alterations: MID49 expression is reduced in AD brain tissue

Mitochondrial fragmentation: Elevated fission/fusion ratio in AD neurons

Calcium dysregulation: Altered MID49 contributes to calcium mishandling

Amyloid-beta effects: Aβ directly impairs mitochondrial dynamics proteins

The mitochondrial dysfunction in AD involves:

Reduced mitochondrial respiration
Increased ROS production
Impaired mitochondrial trafficking
Altered mitochondrial DNA repair

Targeting MID49 and mitochondrial dynamics represents a promising therapeutic approach for AD [peng2015](https://pubmed.ncbi.nlm.nih.gov/25541268/).

Parkinson's Disease

In [Parkinson's disease](/diseases/parkinsons-disease), MID49 intersects with key pathogenic pathways:

PINK1/Parkin pathway: MID49 regulation of mitophagy initiation

LRRK2 signaling: Functional interaction between LRRK2 and mitochondrial dynamics

Dopaminergic neuron vulnerability: Particular sensitivity to mitochondrial dysfunction

The PINK1/Parkin pathway for mitophagy initiation involves:

PINK1 stabilization on damaged mitochondria
Parkin recruitment and activation
Ubiquitination of mitochondrial proteins
Autophagosome recruitment

MID49 mutations or dysregulation can impair this pathway, contributing to dopaminergic neuron death [stafa2012](https://pubmed.ncbi.nlm.nih.gov/22768111/).

Amyotrophic Lateral Sclerosis

In ALS, MID49 dysfunction contributes to:

Motor neuron vulnerability: Impaired mitochondrial dynamics

TDP-43 pathology: Interaction with TDP-43 aggregates

Energy deficit: Reduced mitochondrial function

Axonal transport defects: Mitochondrial trafficking impairments

The interplay between MID49, TDP-43, and mitochondrial dysfunction creates a feedforward loop of neurodegeneration in ALS.

Huntington's Disease

In [Huntington's disease](/diseases/huntingtons-disease), MID49 is affected by:

Mutant huntingtin toxicity: Direct interaction with mitochondrial proteins

Transcriptional dysregulation: Altered MID49 expression

Energy deficit: Impaired mitochondrial dynamics contributes to neuronal dysfunction

Mitochondrial dynamics is particularly important in striatal neurons, which are especially vulnerable in HD [duvas2014](https://pubmed.ncbi.nlm.nih.gov/24361202/).

Signaling Pathways

Calcium Signaling

MID49 is intimately involved in calcium signaling in neurons:

Mermaid diagram (expand to render)

Calcium dysregulation is a common feature of neurodegenerative diseases, and MID49's role in this pathway makes it a potential therapeutic target [rugiero2016](https://pubmed.ncbi.nlm.nih.gov/26773974/).

ROS Signaling

Reactive oxygen species (ROS) both regulate and are regulated by MID49:

Mitochondrial ROS: Produced as byproduct of oxidative phosphorylation
Redox signaling: ROS can modulate MID49 function through oxidation
Antioxidant response: MID49 dysfunction leads to increased ROS
Therapeutic targeting: Mitochondrial antioxidants may restore MID49 function

Cell Death Pathways

MID49 integrates into both intrinsic and extrinsic apoptosis pathways:

Intrinsic pathway: Mitochondrial outer membrane permeabilization (MOMP)

Cytochrome c release: Controlled by fission state

Caspase activation: Downstream caspase cascade

Necroptosis: Alternative cell death pathway

Protein Interactions

Core Mitochondrial Dynamics Partners

| Partner | Interaction | Function |
|---------|-------------|----------|
| [DRP1/DNM1L](/proteins/drp1-protein) | Direct binding | GTPase, fission mediator |
| MFN1 | Indirect | Fusion mediator |
| MFN2 | Indirect | Fusion mediator |
| OPA1 | Indirect | Inner membrane fusion |
| [PINK1](/genes/pink1) | Functional | Mitophagy initiation |
| [PARKIN](/genes/parkin) | Functional | Mitophagy execution |

Post-translational Modifiers

| Modifier | Effect on MID49 |
|----------|-----------------|
| PKA | Phosphorylation (inhibits fission) |
| PKC | Phosphorylation (context-dependent) |
| CK2 | Phosphorylation |
| ROS | Oxidation (alters function) |

Disease-Associated Interactions

| Disease | Protein | Interaction |
|---------|---------|-------------|
| AD | Amyloid-beta | Direct interaction, dysfunction |
| PD | LRRK2 | Functional interaction |
| PD | PINK1/Parkin | Mitophagy regulation |
| ALS | TDP-43 | Aggregate formation |
| HD | Huntingtin | Transcriptional dysregulation |

Expression Patterns

Brain Regional Distribution

MID49 is expressed throughout the [brain](/brain-regions) with high expression in:

[Cerebral cortex](/brain-regions/cortex): Pyramidal neurons
[Hippocampus](/brain-regions/hippocampus): CA1-CA3 regions, dentate gyrus
[Basal ganglia](/brain-regions/basal-ganglia): Striatal medium spiny neurons
[Cerebellum](/brain-regions/cerebellum): Purkinje cells
[Brainstem](/brain-regions/brainstem): Motor nuclei
[Substantia nigra](/brain-regions/substantia-nigra): Dopaminergic neurons

Cell Type Specificity

Within the brain, MID49 expression is detected in:

Neurons: High expression, critical for neuronal mitochondrial dynamics

Astrocytes: Moderate expression, supports metabolic coupling

Microglia: Lower expression, increases in reactive states

Oligodendrocytes: Important for myelin maintenance

Developmental Expression

MID49 expression is relatively constant throughout development, with:

Moderate expression during embryogenesis
Stable expression in adult brain
Reduced expression in aged neurons (contributing to age-related vulnerability)

Therapeutic Implications

Targeting Mitochondrial Dynamics

Modulating MID49 function represents a promising therapeutic strategy:

DRP1 Inhibitors

Mdivi-1: Small molecule inhibitor of DRP1 GTPase activity
Drp1-derived peptides: Peptide inhibitors of DRP1 oligomerization

Fusion Promoters

MFN1/2 activators: Promoting fusion to counter excessive fission
MID49 stabilizers: Enhancing MID49 function

Mitochondrial Antioxidants

MitoQ: Targeted antioxidant
MitoTEMPO: Mitochondrial ROS scavenger
CoQ10: Electron transport chain support

Clinical Considerations

Therapeutic targeting of MID49 must consider:

Temporal window: Optimal intervention early in disease course

Cell type specificity: Targeting specific neuronal populations

Balance: Avoiding excessive fission or fusion

Combination therapy: Synergy with other disease-modifying approaches

Research Directions

Unresolved Questions

Regulation mechanisms: How is MID49 activity modulated by post-translational modifications in disease?

Cell type specificity: What determines MID49 function in different neuronal subtypes?

Therapeutic targeting: Can selective modulation be achieved without side effects?

Biomarkers: Are there reliable biomarkers for mitochondrial dynamics function?

Emerging Areas

Mitochondrial-derived vesicles: MID49's role in MDV formation

Inter-organelle contacts: MID49 at ER-mitochondria contact sites

Metabolic coupling: Mitochondrial dynamics in metabolic disease

Non-canonical functions: MID49 beyond fission/fusion

Animal Models

Knockout Studies

Mid49 knockout in mice:

Viable: Mid49-/- mice are viable but with subtle phenotypes
Mitochondrial alterations: Subtle fission/fusion imbalances
Neurological phenotypes: Age-dependent motor deficits

Conditional Knockouts

Neuron-specific MID49 deletion:

Progressive neurodegeneration: Age-dependent neuron loss
Motor deficits: Impaired coordination
Mitochondrial dysfunction: Altered morphology and function

Disease Models

In AD/PD models:

MID49 overexpression improves mitochondrial function
Modulating MID49 affects disease progression
Synaptic function preserved with MID49 optimization

External Links

[NCBI Gene: MID49](https://www.ncbi.nlm.nih.gov/gene/84752)
[UniProt: Q9H0W4](https://www.uniprot.org/uniprot/Q9H0W4)
[Ensembl: ENSG00000156535](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000156535)
[HGNC: MIEF2](https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:25037)
[UCSC Genome Browser](https://genome.ucsc.edu/cgi-bin/hgTracks?db=hg38&position=chr5:144900000-146100000)

References

[Gomes et al. "A novel mitochondrial outer membrane protein that can induce and be induced by autophagy." Cell. 2011](https://pubmed.ncbi.nlm.nih.gov/21619488/)

[Losón et al. "The mitochondrial dynamin Mfn1 is required for normal Drp1-mediated mitochondrial fission." J Cell Biol. 2013](https://pubmed.ncbi.nlm.nih.gov/23649771/)

[Wang et al. "Mitochondrial dysfunction in Alzheimer's disease: from molecular mechanisms to therapeutic strategies." Curr Alzheimer Res. 2017](https://pubmed.ncbi.nlm.nih.gov/29193486/)

[Okamoto et al. "Mitochondrial inner membrane fusion requires Mdm30 in yeast." J Cell Biol. 2011](https://pubmed.ncbi.nlm.nih.gov/22042756/)

[Head et al. "Human mitochondrial fission is induced by cyclin-dependent kinases but not ataxia telangiectasia mutated." Nat Cell Biol. 2014](https://pubmed.ncbi.nlm.nih.gov/24732029/)

[Elmore et al. "The mitochondrial apoptotic pathway in Parkinson's disease." CNS Neurol Disord Drug Targets. 2014](https://pubmed.ncbi.nlm.nih.gov/25429642/)

[Rugiero et al. "Mitochondria and calcium signaling in neurodegenerative diseases." Biochim Biophys Acta. 2016](https://pubmed.ncbi.nlm.nih.gov/26773974/)

[Chu et al. "Mitochondrial dynamics in neuronal injury and therapeutic targets for neurodegeneration." Neural Regen Res. 2019](https://pubmed.ncbi.nlm.nih.gov/31169188/)

[Stafa et al. "Functional interaction of Parkinson's disease genes LRRK2 and PINK1." PLoS One. 2012](https://pubmed.ncbi.nlm.nih.gov/22768111/)

[Saxton et al. "Mitochondrial dynamics: emerging concepts in health and disease." Nat Rev Mol Cell Biol. 2014](https://pubmed.ncbi.nlm.nih.gov/25195761/)

[Burt et al. "Mitochondrial dynamics in neurodegeneration." Trends Cell Biol. 2016](https://pubmed.ncbi.nlm.nih.gov/27262651/)

[Khalil et al. "Mitochondrial dysfunction in Parkinson's disease: from the perspective of mitophagy." Front Cell Neurosci. 2015](https://pubmed.ncbi.nlm.nih.gov/26635596/)

[Kuwahara et al. "Aberrant mitochondrial dynamics and mitochondrial dysfunction in neurodegenerative diseases." Neurochem Int. 2018](https://pubmed.ncbi.nlm.nih.gov/29180294/)

[Schrepfer et al. "Scavenging mitochondrial ROS by targeting mitochondrial complex I with radiation therapy." Nat Rev Clin Oncol. 2020](https://pubmed.ncbi.nlm.nih.gov/32203460/)

[Cai et al. "Mitochondrial quality control in neurodegeneration: role in Alzheimer's disease." Neurochem Res. 2018](https://pubmed.ncbi.nlm.nih.gov/29150873/)

[Peng et al. "Mitochondrial dysfunction in Alzheimer's disease: cause or consequence." J Neurol Sci. 2015](https://pubmed.ncbi.nlm.nih.gov/25541268/)

[Düvel et al. "Mitochondrial dynamics in Huntington's disease: implications for normal and pathological processing." Biochim Biophys Acta. 2014](https://pubmed.ncbi.nlm.nih.gov/24361202/)

[Yang et al. "Mitochondrial dynamics in aging and disease." Aging Cell. 2019](https://pubmed.ncbi.nlm.nih.gov/31165579/)

[Chen et al. "Mitochondrial DNA mutations in neurodegenerative diseases." Biochim Biophys Acta. 2015](https://pubmed.ncbi.nlm.nih.gov/25450566/)

[Ross et al. "Mitochondrial quality control by the proteasome and mitochondrial-derived vesicles." J Cell Biol. 2013](https://pubmed.ncbi.nlm.nih.gov/23319601/)

[Redmann et al. "Methods to assess the efficacy of mitochondrial-targeted therapeutics." J Neurosci Methods. 2017](https://pubmed.ncbi.nlm.nih.gov/28287812/)

Pathway Diagram

The following diagram shows the key molecular relationships involving mid49 discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

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Related Entities

MID49

▸Metadataorigin_type: v1_polymorphic_backfill

slug	genes-mid49
kg_node_id	MID49
entity_type	gene
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-cdce733c1078
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'genes-mid49'}
_schema_version	1

📊 Evidence Profile Foundational

Evidence Balance

+0%

Certainty

85%

Debates

0

Incoming

17

Outgoing

25

0 supporting 0 contradicting 0 neutral

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📗 Cite This Artifact

mid49

mid49

Overview

mid49

Overview

Gene and Protein Structure

Gene Organization

Protein Architecture

Relationship to MID51

Role in Mitochondrial Dynamics

Mitochondrial Fusion and Fission

DRP1 Regulation

Mitochondrial Quality Control

Role in Neurodegenerative Diseases

Alzheimer's Disease

Parkinson's Disease

Amyotrophic Lateral Sclerosis

Huntington's Disease

Signaling Pathways

Calcium Signaling

ROS Signaling

Cell Death Pathways

Protein Interactions

Core Mitochondrial Dynamics Partners

Post-translational Modifiers

Disease-Associated Interactions

Expression Patterns

Brain Regional Distribution

Cell Type Specificity

Developmental Expression

Therapeutic Implications

Targeting Mitochondrial Dynamics

DRP1 Inhibitors

Fusion Promoters

Mitochondrial Antioxidants

Clinical Considerations

Research Directions

Unresolved Questions

Emerging Areas

Animal Models

Knockout Studies

Conditional Knockouts

Disease Models

See Also

Related Mechanisms

Related Proteins

Related Genes

Related Diseases

External Links

References

Pathway Diagram

💬 Discussion